A power lock actuator is provided for a door lock mechanism of a vehicle. The actuator includes an electric motor, a linear drive, and a slip clutch between the motor and the linear drive. The clutch includes a dual-lobe pinion for pulsed energy transmission from the motor to the linear drive, to provide soft starts and stops, which extend the life of the drive assembly 26. The linear drive includes a screw with multiple, discontinuous male thread segments to minimize friction with female threads on the extendible and retractable carriage, thereby minimizing wear between the screw and the carriage.